A lock of the type described above is disclosed in DE-A-36 43 388. The mechanism for locking the handle shaft comprises a locking lever on the handle shaft and a stop element pivotally mounted about a pivot on the frame between a first position wherein it blocks the locking lever and a second position wherein it enables rotation of the locking lever and, hence, of the handle shaft. The stop element is moved by magnetic attraction thereof, by an electromagnet. Since the pivot of the stop element extends substantially parallel to the handle shaft, the stop element is moved by the electromagnet in a direction which is situated substantially in a plane extending at right angles to the handle shaft.
A drawback of such an arrangement is that the locking mechanism of the handle shaft is difficult to be made very reliable, especially if the lock is used outdoors. For a skilled person, it will indeed be clear that under varying weather conditions and,, as a result of dust or other dirt penetrating into the lock, the required rotation of the stop element in the lock illustrated in DE-A-36 43 388 can be hampered so that the locking mechanism can no longer be operated. Dust or other dirt can penetrate in particular between the stop element and the surface of the frame onto which it slides. The rotation of the stop element can especially also be obstructed in case of frosty weather, when dew or condensation becomes frozen in the lock.
It would therefore be advantageous to provide a new lock wherein the mechanism for locking the handle shaft can be kept simple but rendered more robust or reliable.